Generally, an air conditioner is an apparatus that cools or heats a room using a refrigeration cycle, which includes a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger. The air conditioner may be configured as a cooler to cool a room, a heater to heat a room, or a combined cooling/heating air conditioner, which selectively cools or heats a room.
The combined cooling/heating air conditioner generally includes a 4-way valve, which changes the path of refrigerant, compressed in the compressor, based on a cooling operation and a heating operation. During a cooling operation, the refrigerant, compressed in the compressor, flows to the outdoor heat exchanger by passing through the 4-way valve, and the outdoor heat exchanger serves as a condenser. Then, the refrigerant, condensed in the outdoor heat exchanger, is expanded in the expansion valve, and thereafter introduced into the indoor heat exchanger. At this time, the indoor heat exchanger serves as an evaporator, and in turn, the refrigerant evaporated in the indoor heat exchanger again passes through the 4-way valve to be introduced into the compressor.
During the cooling operation or the heating operation, refrigerant in the compressor may improve the coefficient of performance of a system.
However, the conventional technology of injecting the refrigerant into the compressor during the cooling operation includes bypassing a portion of the high-temperature and high-pressure liquid-phase refrigerant, having passed through the condenser, thus causing deterioration in the cooling ability of an indoor unit due to a reduction in the evaporation flow rate of the refrigerant.